A. Field of the Invention
The present invention relates generally to the field of fall prevention apparatus for rooftop workers, and more particularly to an improved safety rail system for installation about the perimeter of a roof.
B. Description of the Prior Art
During application and maintenance of roofing on buildings, workers are placed at risk of falling from heights which are known to cause serious injury or death. Therefore, insurance companies and governmental agencies such as OSHA now prescribe that a safety barrier be erected about the perimeter of a rooftop work site to prevent accidental falls.
In view of this need, several safety rail systems designed to be erected about a roof perimeter have been proposed. U.S. Pat. No. 3,584,839 to Dickey discloses a system wherein an upright post or stanchion includes a horizontal arm extending inwardly from a bottom portion thereof, and the arm is provided with a downwardly directed spike at its distal end which is sized to fit within a sleeve embedded in poured concrete of the roof. The stanchion includes a pair of spaced apart clamp members for securing overlapping wooden rails to the stanchion.
U.S. Pat. No. 3,880,405 to Brueske teaches a another perimeter safety rail system designed primarily for use on roof construction having a plurality of ribbed roof panels. The system of Brueske includes posts or stanchions which are fixed directly to a base having one of several disclosed attachment means, depending upon where the base and stanchion are to be mounted. Diagonal braces are provided for further supporting the stanchions. This patent shows the use of straps having clips at their opposite ends for connection to a pair of spaced stanchions.
An adjustable roof perimeter guard rail system is shown in U.S. Pat. No. 3,901,481 to Probst. In this system, a base plate is fastened to the roof by nails or other fasteners, and an internally splined bushing is welded to an outer edge of the base plate to extend horizontally with the roof edge. An externally splined shaft is removably mated within the bushing and carries a sleeve fixed to extend tangentially from the shaft, whereby the vertical attitude of the sleeve may be adjusted at discrete angular increments as dictated by the splined fitting. Stanchions or posts are slidably received by the sleeves and include means for supporting a pair of horizontal rails.
An adjustable guard rail stanchion apparatus is disclosed in U.S. Pat. No. 4,666,131 to Kettelkamp, Sr. et al. The apparatus includes an L-shaped stanchion member having pivotally adjustable clamping means at the base of the L for attaching the apparatus to an existing rafter board.
U.S. Pat. No. 4,979,725 to Hutchings, II et al teaches a triangular safety rail support comprising a base leg for attachment to a roof, a diagonal brace, and a telescopically adjustable two-part stanchion having upper and lower stanchion members. The lower stanchion member and the diagonal brace are pivotally connected to the base leg at opposite ends thereof, and a remaining end of the diagonal brace is pivotally connected to the upper stanchion member, thus providing adjustability for accommodating different roof pitches. The stanchion includes means for holding boards serving as horizontal rails.
Another protective system is disclosed in U.S. Pat. No. 5,221,076 to Zust, wherein the base of each stanchion is clamped within an existing gutter, and stanchion support lines are anchored to the roof.
U.S. Pat. No. 5,558,312 discloses an adjustable safety bracket for use in erecting a roof perimeter barricade. An attachment member of the bracket includes a channeled portion for engaging a free end of a roof joist, and a yoked portion extending from the joist for pivotally connecting a support member thereto. The support member is adapted to hold a wooden post for supporting the barricade.
Finally, applicant is aware of a safety rail system marketed by Protective Roofing Products Ltd of Stoney Creek, Ontario, Canada. The system utilizes wedge anchors fixed to a structural wall, and wall clamps, for securing stanchions about the roof perimeter. The stanchions include spaced apart clamping means for securing rail boards to the stanchions.
Shortcomings of the prior art systems mentioned above include labor-intensive and time-consuming installation and removal procedures; bulky rails which may be placed on the rooftop when a section of the guard rail is opened to permit transport of materials, equipment, and workers to the roof, thereby presenting a risk that a worker may trip over a carelessly placed rail; and extensive space requirements for storage and transport.